Help!

Mr B

Put a clamshell type separator clamp under gears and mount it in press bed much like manual, press will load far more evenly than 3 leg puller and you should hopefully have gauge to see hydraulic load . The clamshell type clamp if fits nice takes load to inner gear making less chance of an issue. 3 leg puller foot is right on gear tooth and right at edge of gear so more likely load less evenly plus leverage of contact points is working against you thus making damage to gear more likely if overly forceful. Trouble with those leg pullers mixed with hydraulic ram is you can be putting likes of 10tonne load on small contact foot area .

Cosmic73

Posts : 1093Join date : 2015-10-04Age : 45Location : County Durham

I was planning on doing that tomorrow MrB, this afternoon i already had the puller set up so i tried it with only gentle persuasion. In any case it was too bastard tight so i backed off because its Pete's call.The bottom line is 1st synchro ring us stuffed, needs replacing and 2nd/3rd gears must be removed to access it.Pete's given me the green light to carry on so thats what ill do.One thing thats standing out is a comment Pete made. He said the fitter had to use considerable force to press these gears as they were really tight.A potential theory of mine is that if the press tonnage is massively high, how do you know if its come to the shoulder? Maybe its gone beyond it and deformed it?Soon find out tomorrow, im taking a video of it which ill post.

Cosmic73

Posts : 1093Join date : 2015-10-04Age : 45Location : County Durham

Pete's gearbox failed in 3rd gear and it's 3rd gear that can not pressed off.I'm fast coming to the conclusion that the 3rd gear splines have twisted which is why the gear cant be removed. But this will be confirmed once its all apart.

Clamshell could not be used due to interference from the synchro underneath 3rd gear;

Hydraulic puller was used instead with 3x wide jaw pullers offering good support across at least 2 teeth per jaw,

Below are the video clips showing the 3rd gear non-removal!

So, the shaft must be cut in half then precision bored to free 3rd gear.

burrows1980

Posts : 781Join date : 2013-09-21Age : 38Location : N. Wales

I think you need to have some Weetabix Neil and have another go fair play though that's pretty much stuck!! Gearbox I s the only thing I've never stripped down and played with, I'm finding this really interesting stuff.. Sorry Pete

PartyPete

the one star club

Posts : 1935Join date : 2014-01-27Age : 32Location : Derbyshire

I believe he has put around 2 tons of force on to try pulling them off, previous fails were just broken gears Johnny so I can't see it being that, I'm finding it interesting in a strange expensive irritating way. I've never known so much about gear boxes, stu that's a very kind offer, I'll bare it in mind, I do have a spare shaft so I'll check it's all a1 before I take it,if not I'll deffo give you a shout!

Mr B

Possible with 1st syncing engagement caused massive load to 3rd at time until synchro got ripped up.It possibly would press off in bench press if can get or make good fitting plates to go under the gear so can put some decent press load on it. If can't then doing what can to get gears off undamaged is best way forward .

Cosmic73

Posts : 1093Join date : 2015-10-04Age : 45Location : County Durham

OK, I'm pretty sure I'm getting closer to solving Pete's problem and I've uncovered a systems flaw with all straight cut gears. I will be sending an email to PAR notifying them of this.It's all to to with straight cut gears generating no axial load, which is good thing right?This is can be wrong because the axial loads cancel out the even bigger and truly massive axial loads generated by the Final drive gear which is still helical.

I've modeled a stock and PAR gearbox in the design software i use.(Please excuse the crudity of the models, i didn't have too much time to work on these)

As i will show switching to straight cut gears generates massive loads rightwards towards the odd geared synchros!

So below is a stock gearbox, note the helix angles on the mainshaft are left handed. There is good reason for this;

Below is an animation in 3rd;

Below shows the powerflow in 3rd,How can the 1st gear synchro and 1st gear engage while in 3rd???

Below shows the mainshaft forces while in 3rd of a stock gearbox.This is only with an input torque of 165Nm (approx 50kw)3rd gear is left handed helix and being driven so it generates a leftward axial load.Final drive gear is also left handed but is Driving (not driven) and therefore generates a rightward axial load. Note the difference in the forces;

ducie54

Cosmic73

Posts : 1093Join date : 2015-10-04Age : 45Location : County Durham

Yes, If you fit PAR gears, you should also fit straight cut final drive gears, brace the case and have zero slop in the manshaftI think this explains why so many straight cut gear boxes are being wrecked.PAR gears are undoubtedly stronger, but it migt unbalances the gearbox as a system which wasn't design for straight cut gears.

Last edited by Cosmic73 on 15th June 2016, 3:50 pm; edited 1 time in total

Mr B

I have straight set with standard final & no issues so far in over 2 years & 2 boxes I done with the par kit, straightcut final is recommended & they advised that to me for drag and high torque . they do a lot of gearkits wiith straightcut & helical final retained so would of thought they done plenty modeling & testing on it . PPG do same on their straightcut syncro & straightcut dog drag box which retains standard final drive unless order it as an addition .The final drive gear is part of the mainshaft so axial load goes direct to the rear shaft bearing & if shaft been setup with correct preload it will not have any shaft shuttling & deflection is down to box rigidity.I use resin & plate end casing brace as still retain the helical drive which loading bearing area heavily .I would be more inclined think mainshaft preload set well off or not even checked when built & float caused alignment issue with hubs & the failure. Hard to be conclusive without seeing it fully stripped & not knowing what floats & preloads seemed like prior to strip down . If he needs new shaft it would be good to go for new par final drive to be more bullet proof .Hopefully the gear splines are not damaged, shaft is softer so favorable chance they reusable .Part of reason why you don't want reduce preloads to much in track use is because force and deflection has more end result in shaft axial bearing setup than what additional heat & expansion does unless on full straightcut kit .

Cosmic73

Posts : 1093Join date : 2015-10-04Age : 45Location : County Durham

@Mr B wrote:I have straight set with standard final & no issues so far in over 2 years & 2 boxes I done with the par kit, straightcut final is recommended & they advised that to me for drag and high torque . they do a lot of gearkits wiith straightcut & helical final retained so would of thought they done plenty modeling & testing on it . PPG do same on their straightcut syncro & straightcut dog drag box which retains standard final drive unless order it as an addition .The final drive gear is part of the mainshaft so axial load goes direct to the rear shaft bearing & if shaft been setup with correct preload it will not have any shaft shuttling & deflection is down to box rigidity.I use resin & plate end casing brace as still retain the helical drive which loading bearing area heavily .I would be more inclined think mainshaft preload set well off or not even checked when built & float caused alignment issue with hubs & the failure. Hard to be conclusive without seeing it fully stripped & not knowing what floats & preloads seemed like prior to strip down . If he needs new shaft it would be good to go for new par final drive to be more bullet proof .Hopefully the gear splines are not damaged, shaft is softer so favorable chance they reusable .Part of reason why you don't want reduce preloads to much in track use is because force and deflection has more end result in shaft axial bearing setup than what additional heat & expansion does unless on full straightcut kit .

Those deflections were at zero pre-load at the bearings, eg zero clearance so it's system deflection only that i considered. If i had've included any bearing clearance issues the displacements would be worse again..Yes FD axial load is transferred directly to the rear bearing then it goes to the case which deflects, so the entire mainshaft moves rearwards.But now it's got 3x more force behind it.

You make a good point about bracing, and yes this could be a solution.

So Pete's choices;Rebuild 'again' with PAR gears, stock FD and cross fingers,Rebuild with PAR gears and brace the mainshaft bearing surfaces of his case,Rebuild with PAR gears and straight cut final drive,Fuck the whole thing off and buy an EVO,

Last edited by Cosmic73 on 17th June 2016, 8:35 pm; edited 4 times in total